Biopsy instruments of the prior art are generally biopsy needles which are sued by hand or biopsy guns which together with biopsy needles are used to obtain samples. The biopsy needles of the prior art have been directed to bone biopsy needles and to soft tissue biopsy needles. The biopsy guns of the prior art have been directed to soft tissue biopsy guns.
Bone biopsy needles have generally been cumbersome and very difficult instruments to use. As a result, bone biopsy procedures using bone biopsy needles are generally painful and traumatic procedures. The doctor manually inserts a needle through the skin into the bone and because the bone is hard the needle is very difficult to insert. It requires a lot of strength to push the needle into the bone. Once the needle is inserted into the bone, the needle is manipulated in an attempt to break off a piece of bone in the needle and then a syringe is placed on the end of the needle to aspirate the liquid bone marrow up into the needle. Unfortunately, often the liquid bone marrow can not properly be retained in the needle because the bone sample in the needle is blocking the entrance into the needle and thereby blocking the passageway for the liquid bone marrow. Furthermore, the bone sample is difficult to maintain in the needle. As a result, bone biopsies using such needles are not only painful and traumatic but are quite often not completed properly since the liquid bone marrow sample and the cored solid bone sample are not properly retained in the needle.
The Jamshidi needle of the prior art is used for obtaining bone biopsies and is the current standard means for obtaining such biopsies. The needle comprises a hollow tube, one end of which is swaged to taper the end. As the tapered end penetrates the bone marrow, a core of the tissue passes into the lumen of the needle and the tapered end is manipulated to cut off the cored bone. This needle does not provide an adequate mechanism for removing the liquid bone marrow since the opening on the needle is effectively plugged by the cored bone.
Most of the soft tissue biopsy needles of the prior art are generally known as tru-cut type needles. Tru-cut needles have a gutter drilled out of one end of the needle and a cannula or sleeve which slides over the gutter. After the tru-cut needle is inserted into the soft tissue, the soft tissue falls into the gutter and the cannula is then pushed forward over the gutter slicing the tissue off into the gutter. As the true-cut needle is withdrawn, the tissue is maintained in the gutter.
There are also other types of soft tissue biopsy needles, such as the soft tissue biopsy needle described in U.S. Pat. No. 4,903,709 to Skinner. Skinner describes a soft tissue needle in which there is a lanced portion formed from the sidewall of the needle which lanced portion assists in slicing the soft tissue.
The soft tissue needles of the prior art are not suitable for bone biopsies. The soft tissue needles are not strong enough to withstand the force on the needle necessary to penetrate the bone. Furthermore, with respect to the tru-cut needles, the bone tissue is too hard and as such it does not fall into the gutter of the needle and therefore is not appropriate for bone biopsies. With respect to the biopsy needle described in Skinner, it is not suitable for bone biopsies as there is no means for obtaining a liquid bone marrow sample in the needle. A proper bone biopsy requires a sample of the liquid bone marrow as well as a sample of the solid bone.
There are many biopsy guns of the prior art which are used together with a biopsy needle. The biopsy guns of the prior art are designed to be used to biopsy soft tissues often with a tru-cut needle and are not suitable for bone biopsies, as described above. The biopsy gun fires the tru-cut needle into the larger soft tissue and as the needle penetrates the soft tissue the soft tissue falls into the gutter. The biopsy gun then fires a metal sheath or cannula on the needle over the gutter slicing the soft tissue off into the gutter.
U.S. Pat. No. 5,146,921 to Terwilleger et al. describes a biopsy instrument for removing soft tissue sample. The soft tissue penetrating needle has an inner stylet and a cannula. The inner stylet penetrates the soft tissue mass. The inner stylet is notched so that when the stylet penetrates the soft tissue a portion of the soft tissue falls into the notched area. The cannula then slides over the stylet severing the soft tissue in the notched area. Both the penetration of the inner stylet into the soft tissue and the severance of this soft tissue by the cannula are actuated by actuating a fire button. A second button, a retraction button, can then be depressed to retract the canula. Then the second button is retracted a second time to retract the stylet from the soft tissue. The actuation of the stylet and cannula is possible by the rotary motion of a special cam assembly. There are essentially three positions of the bone biopsy gun; where both stylet and cannula are forward; where the stylet is forward and the cannula is retracted; and where both the stylet and cannula are retracted. This biopsy instrument is not suitable for bone biopsies since, among other things, the bone tissue could not be collected using the needle described.
U.S. Pat. No. 5,234,000 describes an automatic biopsy device housing a plurality of stylets to permit multiple soft tissue biopsy samples to be taken. The stylets are used in conjunction with a cannula. The device is operated by an actuating trigger means which propels the stylet through the cannula into the target organ so that a portion of the soft tissue enters a recess of the selected stylet and then the cannula is propelled over the stylet slicing the soft tissue into the recess. When the trigger is released the stylet and cannula retract out of the target organ.
U.S. Pat. No. 4,461,305 describes an automated biopsy device for automatically extracting soft tissue samples, particularly from the uterine cervix. The device has a core-cutter which is advanced into the target tissue to a certain depth cutting away the soft tissue as it penetrates the soft tissue by depressing an actuated trigger. When the trigger is released the rotation of the core cutter ceases. A reset knob is then manually rotated by the operator to return the core-cutter to the original position.
As discussed above, the biopsy instruments and needles of the prior art which are used for obtaining soft tissue samples are not suitable for bone biopsies. A bone sample, including a liquid bone marrow sample, can not be properly obtained with these prior art instruments and needles. In particular, with respect to the stylet and cannula assemblies of the prior art, the bone sample would not fall into the notched area in the stylet and therefore a bone sample could not be obtained. In addition, these instruments have not been designed to withstand the forces exerted on the needle during a bone biopsy in contrast to a soft tissue biopsy.
It is desirable to have a biopsy instrument which is designed so that it has enough force to effectively sample bone tissue. It is also desirable to have a biopsy instrument which is hand held and is designed so that a bone sample may be taken requiring very little, if any, manual strength. Furthermore, it is desirable to have a biopsy instrument which can be used to obtain a bone sample and a liquid bone marrow sample in a single biopsy procedure. It is also desirable to have a biopsy instrument that makes the biopsy process less traumatic and painful, requires less time to conduct and requires less operator expertise and therefore is more reliable, reducing multiple procedures.
A proper bone biopsy requires both a bone sample and a liquid bone marrow sample. The procedure as practised suing the prior art bone biopsy needles is painful and requires an operator's strength and skill. Often, multiple attempts are necessary to obtain a proper bone marrow biopsy. Furthermore, for bone marrow disease it is often desirable to take bone biopsies successively and repeatedly at different intervals to monitor the progress or regression of the disease increasing the anxiety of the patient in view of the pain caused by the procedure. Accordingly, it is desirable to provide a more reliable biopsy instrument, requiring less operator expertise, reducing the likelihood of multiple attempts and reducing the time required to take a biopsy sample.
It is also desirable to have a biopsy instrument comprising a biopsy gun and a biopsy needle which can be used to obtain a bone sample and a liquid bone marrow sample in a single bone biopsy procedure or which can be used to obtain a soft tissue sample in a single soft tissue biopsy procedure.